I think this is normal.

Normal. Almost everything will look different when wet. It is the same as pulling a beautiful shiny rock out of the ocean only to have it dry out and look dull and 'boring'. Same concept different material. "Wet" alters the appearance of any product. The GOOD news is it goes back to the original colour. That tells you the seal is working. It's when it stops going back to the original colour is when you know it is time for a bit of TLC.